Traditionally, testing of integrated circuits may be accomplished using several different techniques, many of which are complicated with various issues. In a first scenario, for instance, a retest pass may be performed that is separate from an initial test pass. For example, a lot testing cycle may include a first pass, a retest pass, and a quality assurance (QA) pass. After finishing the first pass, the test operations may need to be paused in order to calculate the first pass test results, and to prepare for the next test pass. For example, the next test pass may be a retest pass, a QA pass, etc. However, the work flow in this scenario significantly increases the operational overhead involving human operators, which may further cause unnecessary human errors.
FIG. 1 illustrates performing a retest on all failed devices, in accordance with a second scenario. For example, a lot of device XYZ may contain 10,000 devices that have undergone a first pass of testing 110. Of these 10,000 devices, 9,000 of them passed (see item 112), and 1,000 of them failed (see item 114) a first pass of testing 110. The target yield for device XYZ is 92%. During the first pass of testing 110, the lot has achieved a 90% yield, as shown. Therefore, the lot may have to go through a retest pass in order to meet the 92% target yield. An operator may thus gather the 1,000 failed devices and then prepare for a secondary retest pass 150.
In order to achieve the aforementioned target, 200 devices need to pass in the retest pass 150. For example, it may be assumed that, after testing 400 devices, 200 devices are passed. The 200 passing devices result in the overall lot yield achieving the 92% target yield. However, all remaining 600 devices of the 1000 retest pass must be retested, since the retest pass 150 is separate from the first pass of testing 110. Since the retest pass 150 is separate from the first pass of testing 110, the system cannot perform the internal and automatic calculations on the overall lot yield. Hence, the testing process is unable to make a decision on the necessity of the retest for the remaining 600 devices. Therefore, the existing final test pass is considered inefficient and may require a longer duration for testing.
In yet another scenario, a retest may be performed on a low bin recovery rate. In use, a single lot may contain numerous bins of devices. For example, during the retest of the lot for a device XYZ, it may be difficult to control the process of skipping the retest of a particular bin. Therefore, numerous unnecessary retests may have been performed during the retest pass.
In still yet another scenario, a loss of a first pass test bin result may take place. For example, since the first pass and retest pass may take place separately, the correlation between a first test bin result and a retest bin result for a particular device may be unavailable. After the testing completes, a product engineer may need to know the recovery percentage of each bin that failed in the first pass and recovered in the retest pass. However, it is time consuming to keep track of the test bin result and handle the devices being tested between the first pass and the retest pass.
There is thus a need for addressing these and/or other issues associated with the prior art.